Key retainers or cases are very widely used in everyday life, and there are numerous such devices described in many patent specifications; for example, in Hughes' U.S. Pat. No. 4,045,983, McDonald's U.S. Pat. No. 4,045,984, and Youd's U.S. 4,037,439.
Construction of these known devices in most cases is relatively unsophisticated in the sense that it ensures only one function; namely, the storing of keys, held in a bunch.
In known key retaining devices selection of the demanded key and its movement from stored position to use position is manually allowed only after the user has made direct observation of the whole plurality of keys stored in the retainer and has visually identified and selected the proper key. In darkness, or in insufficient lighting conditions, manipulation of such retainers can be difficult and rather inconvenient, especially for weak-sighted persons, since it is impossible to identify and select one of a plurality of keys without previous visual contact.
The other disadvantage of known key retaining devices is associated with the fact that their construction does not allow for fixation of the key by the holder after it is moved to a use position. In order to effect the key; for example, when it is inserted in the key way, it should be firmly grasped by the fingers. Due to this limitation the ultimate rotational force which can be applied to the key becomes dependent on the physical ability of the person using the key and on the dimensions of the key. This might cause additional inconvenience, especially for small children or disabled persons.
Another common drawback inherent to known key retainers is that their external size is dependent on the dimensions of the keys to be stored, and in particular, on the width of the key handle. When keys with wide handles are stored, the holder becomes rather bulky, cannot be put in a pocket, and might even require manipulation by both hands.
In conclusion, it should be pointed out that despite the existence of numerous key retaining devices, there is still a need for a new, improved, simple and convenient-to-use key retainer.